P3C024: Every Ptosis Is Not Myasthenia Gravis! : An Unusual Case of Neuropathy in Dermatomyositis

Introduction: Dermatomyositis is a rare autoimmune disorder which typically presents with myopathy and rash. Rarely, initial symptoms may include ptosis, presenting a unique diagnostic challenge in the adult and pediatric population.

Case Description: We present the case of a seventeen-year-old female with past medical history of Ehlers Danlos Syndrome who presented with new onset history of weakness. Weakness initially began with ptosis and diplopia. This was followed by weakness in her upper and lower extremities and dysphagia. At the time of admission, the patient was wheelchair-bound secondary to frequent falls. She later developed an erythematous, photosensitive rash on her face and chest along with unilateral, rash on her right lower extremity and wrist, accompanied by arthralgia. At the time of admission, the patient was afebrile and lab work including CBC, CMP, TSH, ESR, CRP and COVID 19 was unremarkable. Imaging studies including CT Head and MRI Brain and Spine showed no acute abnormality. Lumbar puncture was completed, and CSF studies were unremarkable. Further lab tests including folic acid, vitamin-D urine drug screen, vitamin B12, thyroid peroxidase thyroglobulin, RPR, ANA, aldolase, lactate, SSA, SSB, aquaporin antibodies and CK were within normal limits. Due to concern for presenting ptosis and weakness, there was concern for Myasthenia Gravis. She was started on Mestinon, IVIG and Solumedrol. She initially experienced some clinical improvement however exhibited persistent weakness. EMG was notable for chronic myopathic changes. MRI bilateral thighs was without inflammatory changes or fatty infiltration. Myomarker panel was positive for anti-NXP-2 antibody. As such, she was diagnosed with NXP-2 Juvenile Dermatomyositis and started on Methotrexate and Rituximab. On follow-up patient’s rash and weakness improved, however her arthritis worsened with noted contractures. Hydroxychloroquine was then initiated. She continues to follow with P, Neurology and Rheumatology.

Discussion: NXP-2 is associated with 25% of Juvenile Dermatomyositis cases. The disease is significantly associated with rash as in our patients. Further, there is an association with malignancy in adults and calcinosis in pediatric patients. Research has shown that patients with this subtype of dermatomyositis have more severe muscle involvement and are less likely to enter remission. They often require more aggressive treatments and close follow-up with Rheumatology, PT and OT.

Conclusion: While Dermatomyositis typically presents as a myopathy with findings on MRI, this patient presented with atypical myopathy with neuropathic features. This is unusual for dermatomyositis. Nuclear Matrix Protein 2 Juvenile Dermatomyositis is associated with cancers in adult patients, and calcinosis with contractures as in our patient. It is a severely debilitating diagnosis, particularly in a patient as young as this. It often presents with severe manifestations requiring more aggressive treatment. Pediatricians and Rheumatologists must keep NXP dermatomyositis on their differential despite presenting symptom of ptosis which may initially raise suspicion for a neurologic disorder.